Static Test Compaction for Scan-Based Designs to Reduce Test Application Time

We propose a static compaction procedure to reduce the test application time for full and partial scan synchronous sequential circuits. The procedure accepts as input a set of test subsequences. A test subsequence consists of a sequence of primary input vectors, and a vector to be scanned-in before the input sequence is applied. The procedure uses two operations to reduce the test application time. The first operation combines test subsequences. The second operation reduces the lengths of the combined subsequences (the length of a test subsequence is the length of the input sequence included in it). The reductions in test application time of the proposed procedure are demonstrated through experimental results.     

Space-Time Diversity Using Orthogonal and Amicable Orthogonal Designs

In this paper we consider the utilization of multiple transmitterand receiver antennas for space-time diversity. The optimalSNR scheme, which also provides the best diversity, is outlined.This scheme however involves a reduction in the data rate. Coding schemes are then presentedwhich not only achieve the optimal SNR but also mitigate the reductionof data rate. The proposed schemes are based on the theory of Orthogonal Designsand Amicable Orthogonal Designs.     

The Theory of Quaternion Orthogonal Designs

Over the past several years, there has been a renewed interest in complex orthogonal designs for their application in space-time block coding. Motivated by the success of this application, this paper generalizes the definition of complex orthogonal designs by introducing orthogonal designs over the quaternion domain. This paper builds a theory of these novel quaternion orthogonal designs, offers examples, and provides several construction techniques. These theoretical results, along with the results of preliminary simulations, lay the foundation for developing applications of these designs as orthogonal space-time-polarization block codes.     

Hazard-Based Detection Conditions for Improved Transition Fault Coverage of Scan-Based Tests

We define a new type of detection conditions for delay faults, referred to as hazard-based detection conditions, to enhance the coverage of delay faults using the standard scan test application methods. Some delay faults, including irredundant faults, may be undetectable under the conventional detection conditions. These faults may be detectable under the hazard-based detection conditions. The use of hazard-based detection conditions thus improves the delay fault coverage achievable for a circuit. We consider transition faults under standard scan for the study in this paper.      

基于正交设计的空时分组码

对基于正交设计的空时分组码进行了研究。描述了在无线信道中多个天线发射的数学模型,研究了空时分组码与正交设计的联系,并且研究了正交设计在多个发射天线的无线通信系统中的应用。对正交设计进行了推广,开发了广义正交设计理论。     

Constructing Space-Time Trellis Codes Using Orthogonal Designs

In this paper we consider the design of space-time trellis codes usingorthogonal designs. We derive a condition on the codewords to obtainthe maximum received signal energy and show that the codes based onorthogonal designs satisfy this condition.We consider in detail the design of a trellis code for two transmitantennas. The new code we develophas a higher diversity in fast fading and a higher coding gain in quasi-static fading when compared to otherexisting space-time codes. We also consider a turbo implementation ofthe new trellis code which results in very high diversity gains infast fading channels.     

On Space-Time Block Codes from Complex Orthogonal Designs

Space-time block codes from orthogonal designs recently proposed by Alamouti, and Tarokh-Jafarkhani-Calderbank have attracted considerable attention due to the fast maximum-likelihood (ML) decoding and the full diversity. There are two classes of space-time block codes from orthogonal designs. One class consists of those from real orthogonal designs for real signal constellations which have been well developed in the mathematics literature. The other class consists of those from complex orthogonal designs for complex constellations for high data rates, which are not well developed as the real orthogonal designs. Since orthogonal designs can be traced back to decades, if not centuries, ago and have recently invoked considerable interests in multi-antenna wireless communications, one of the goals of this paper is toprovide a tutorial on both historical and most recent resultson complex orthogonal designs. For space-time block codes from both real and (generalized) complex orthogonal designs (GCODs) with or without linear processing, Tarokh, Jafarkhani and Calderbank showed that their rates cannot be greater than 1. While the maximum rate 1 can be reachedfor real orthogonal designs for any number of transmit antennas from the Hurwitz–Radon constructive theory, Liang and Xia recentlyshowed that rate 1 for the GCODs (square or non-square size) with linear processing is not reachable for more than two transmit antennas.For GCODs of square size, the designs with the maximum rates have been known, which are related to the Hurwitz theorem.In this paper, We briefly review these results and give a simple and intuitive interpretation of the realization. For GCODs without linear processing (square or non-square size), we prove that the rates cannot be greater than 3/4 for more than two transmit antennas.     

Decoding, Performance Analysis, and Optimal Signal Designs for Coordinate Interleaved Orthogonal Designs

Space-time block codes (STBC) using coordinate interleaved orthogonal designs (CIOD) proposed recently by Khan and Rajan allow single-complex symbol decoding and offer higher data rates than orthogonal STBC. In this paper, we present the channel decoupling property of CIOD codes. A new general maximum likelihood method is derived, enabling the calculation of the symbol pair-wise error probability and union bound (UB) on symbol error rate (SER). Extensive simulation results show that the UB is within 0.1 dB from the simulated SER when SER < 10^-2. The UB thus can be used to accurately predict and optimize the performance of CIOD codes. Furthermore, a new signal design combining signal rotation and power allocation is presented for constellations with uneven powers of real and imaginary parts such as rectangular quadrature amplitude modulation.     

Fault Diagnosis with Imperfect Tests

This paper derives a minimum s-expected cost sequence of built-in-tests (BITs) which will partition modular equipment into mutually exclusive groups of modules. After a fault in the equipment, one of these groups will be identified by a BIT diagnostic subsystem as the group which contains a faulty module. The BITs are imperfect in the sense only that they might not detect all of the possible faults in the equipment; they are perfect in the sense that fault indications are never false. The proportion of faults detectable by each BIT is known. Both the cost of a BIT and the probability that a BIT will pass or fail are functions of which modules are tested. A recursive algorithm is developed which determines a sequence of BITs with a minimum s-expected life-cycle cost. The recursive algorithm is applied to a 4-element numerical example. The algorithm has neither been proved nor implemented for a computer.     

非线性容差电路的故障诊断

文章着重讨论如何根据容差电路有限可及点上的电压测量，诊断其线性和（或）非线性元件故障，文章利用Ｇｒａｓｓｍａｎｎ流形中的子空间距离证明了ε－故障锥的存在，并由此导出容差干扰下的可诊性条件。为了区别非线性元件的自身故障与似故障。本文仔细分析了可及点电压变化阵的方向能量椭球，并提出了相对方向能量准则。仿真表明，该准则对容差影响是鲁棒的。     

容差网络故障诊断中的误差分析

在用双向能量正交法对网络进行故障诊断时，网络的空差会影响结果的准确性。本文分析了由网络容差所造成的误差，给出容差所造成的能量误差的一个上界。在容差统计特性已知的情况下，对判别其偏差是否由故障引起的一个概率上的估计。     

Distributed Diagnosis of Interconnections in SoC and MCM Designs

An interconnect test and diagnostic scheme based on distributed BIST resources in SOC and MCM designs is described. Test and diagnosis is enabled by embedding cascaded test pattern generators and reconfigurable signature analyzers into the design. The theory of partitioning of linear registers is applied to devise a two phase distributed diagnosis strategy. The design of a novel MISR reconfiguration scheme that enables high diagnosis resolution is presented.     

Novel Constructions of Improved Square Complex Orthogonal Designs for Eight Transmit Antennas

Constructions of square, maximum rate complex orthogonal space-time block codes (CO STBCs) are well known, however codes constructed via the known methods include numerous zeros, which impede their practical implementation. By modifying the Williamson and Wallis-Whiteman arrays to apply to complex matrices, we propose two methods of construction of square, order-4n CO STBCs from square, order-n codes which satisfy certain properties. Applying the proposed methods, we construct square, maximum rate, order-8 CO STBCs with no zeros, such that the transmitted symbols are equally dispersed through transmit antennas. Those codes, referred to as the improved square CO STBCs, have the advantages that the power is equally transmitted via each transmit antenna during every symbol time slot and that a lower peak-to-average power ratio (PAPR) is required to achieve the same bit error rates as the conventional CO STBCs with zeros.     

Ping命令与故障诊断

Ping命令目前是在故障诊断中最常见使用的故障诊断和排除命令,详细探讨了Ping命令的用法,并与实际的网络故障现象结合起来讨论其在网络故障诊断与分析中的应用。     

Soft Fault Feature Extraction in Nonlinear Analog Circuit Fault Diagnosis

Aiming at the problem to diagnose soft faults in nonlinear analog circuits, a novel approach to extract fault features is proposed. The approach is based on the Wigner–Ville distribution (WVD) of the subband Volterra model. First, the subband Volterra kernels of the circuit under test are cleared. Then, the subband Volterra kernels are used to obtain the WVD functions. The fault features are extracted from the WVD functions and taken as input data into the hidden Markov model (HMM). Finally, with classification of features using HMMs, the soft fault diagnosis of the nonlinear analog circuit is achieved. The simulations and experiments show that the method proposed in this paper can extract the fault features effectively and improve the fault diagnosis.     

客运索道故障诊断专家系统的开发

索道故障诊断专家系统的建立有利于工作人员在最短的时间内根据故障的表面现象确定其深层原因,从而能够尽快排除故障.     

A Method on Analog Circuit Fault Diagnosis with Tolerance

In this paper, it is proved that the direction of the node-voltage difference vector, which is the difference between the node-voltage vector at faulty state and the one at the nominal state, is determined only by the location of the faulty clement in linear analog circuits. Considering that the direction of the node-voltage sensitivity vector is the same as the one of the node-voltage difference vector and also considering that the module of the node-voltage sensitivity vector presents the weight of the parameter of faulty element deviation relative to the voltage difference, fault dictionary is set up based on node-voltage sensitivity vectors. A decision algorithm is proposed concerned with both the location and the parameter difference of the faulty element. Single fault and multi-fault can be diagnosed while the circuit parameters deviate within the tolerance range of 10 %.     

Fault Diagnosis by Mathematical Programming

This paper presents the problem of fault diagnosis for logically represented continuous systems that can be formulated through nonlinear mathematical programming. This problem is transformed to an integer-programming problem and solved. Possible modifications and extensions of the problem are given. Although failure tables must be prepared in ordinary fault diagnosis, they are not necessary with this mathematical programming approach. By modifying constraints in the mathematical programming problem, difficulties such as multiple faults, correlated faults, modifications of test conditions and cycles in the system, which are encountered in the ordinary failure table approach, are made tractable.     

MiniSAT求解器在电路故障诊断中的应用

MiniSAT求解器运用到电路故障诊断系统时,能够将判断一个电路是否存在故障问题转换为可满足性问题.本文将全加器的行为模型及观测分别使用合取范式（CNF）形式文件描述,调用MiniSAT求解器判定可满足性.该方法自动化程度高,能处理大规模的运算电路,具有较强的查找错误能力.     

基于遗传算法的故障诊断的研究

介绍了遗传算法在故障诊断中的应用，显示出将遗传算法应用于故障诊断可减少运算量、缩短平均诊断时间、提高诊断效率和故障识别精度。